The engine sound from Amiga Lotus Turbo Challenge II.
When you turn it on, it can play the theme music.
(first thought was benny hill theme music, already mentioned, and then the screams of souls eternally trapped in hell, but I guess partially covered by the poll).
Normal bicycles are silent, and can go pretty fast too. Why can't the same solution be used for e-Scooters, a bell?
Have you heard the Get-Ir e-Mopeds? No, just a faint whirr, and again, no problem there apparently.
Just the singling out of e-Scooters, because they're more affordable to the common pleb. But I would support a lower max speed in consumer models (especially targeted at younger people who will use them on pavements).
Biting the hand that feeds IT
